Strange problem with AC.

[FailMechanic]

I was having a problem with my compressor (facotry installed AC), the compressor was cycling on and off so I put my gauages on it and found that the low side and high side were almost 0 (leak!). Anyway, I found the leak, repaired it and put a vacuume on it, I then charged the system (95 deg. outside) with low side at about 45 and high side sitting between 250-275. Now I am having some strange intermittent compressor issues. After I was done charging I turned the AC of and then back on and the clutch did not engage however I had 12 volts to the switch on the compressor. I then hit the clutch plate and it engaged. The compressored stayed running at idle for almost 1 hr. and did not cycle on or off however the pressures above remained steady according to my gauage. This morning (after charging last night) I fire up the truck and turn on the AC and the clutch engaged and blew cold air. The problem is about 20 miles down the road the compressor kicked off. I tried a trick last time I had this problem which was to downshit momentarily at 60 mph to 4th gear which raised my rpms and forced the compressor to kick back on it did not stay on long after I went back to 5th and lowered the RPM's. I left the AC on and it came back on after about 15 min. but only for a brief time. I noticed that if I turned the AC off for 10 or 15 min. (sometimes more) and then turn it on the AC will run for another 15-20 min or so and then kick off. I have replaced the low pressure switch...

Please help it's almost 100 deg. with heat index here!

 

[shadetree]

I would add more refrigerant. 45 low side is too high, especially on a hot day. Ford compressors do not always cycle when it is hot, depending on the vehicle. They run continuously. I like the low side below 40. The book calls for 1.38lb of refrigerant.shady

 

[FailMechanic]

Add more refrigerant or take some out? I thought the more refrigerant you added the higher the pressure on the low side?

Update: I was driving home from work today and the compressor was on almost the whole way home (about 35 min) Yea! The problem is the compressor kicked off about 10 min. before I got home and it would not kick back on. When I got to the house I pushed the clutch plate in and the darn thing kick right in which I assume means the switch on the cluth is engaged so the compressor should have been running? Not sure why it would have disengaged in the first place and why when is disengages would it not re-engage? Do I need to replace the cluth? My wife was also running around at lunch time with it today and she said it was working for about 10 min. and then just stopped. Once she picked me up about 15 min. later (she had turned the compressor to off at this point) it engaged with no problems. It seems that when the rpms get high it tends to disengage more or maybe that's just when it gets hot?

Also, I noticed a new issue today with the AC running, about once every 10 min or so (kinda spuradic really) the air would be directed from the ac vents in the front to the defroster vents and would eventually switch back a few minutes later.

 

[mattpresley]

Please help it's almost 100 deg. with heat index here!

BOO HOO its at least 105 here every day this time of year

 

[FailMechanic]

New Insight

okay so I think I have narrowed down the issue...

This morning on the way to work the AC ran for 10-15 min and then the compressor kicked off. If it turned the AC switch to off for 5 min. or so and then turned it back on the compressor would "usually" kick back on. I did find that the compressor kicked off right before I pulled into the parking garage at work so I opened the hood and hit the cluth and low and behold it kicked in so the circuit to the compressor was closed. My question is could this possibly be a problem with the clutch? Is there anyway to repack bearings or verify the tension on the clutch? This AC has about 300,000 miles on it and I have not had a problem till now so all in all it's been great. I am still having a problem with it constantly switching between AC vents and Defrost vents but as long as the compressor is running and the air is cold I don't care where it's coming out right now.

WoW Arizona, I bet it is a hot MF-er there...it's the humity fairly low there though? I live in Texas on the cost so I'm constantly seeing a heat index of a little over 100 degress with almost 100% humidity...

 

[Earl43P]

The gap is too great for your clutch to engage, meaning the material on the clutch plates have worn down, creating the larger gap.

Replace the compressor clutch. Simple as as that.

 

[SHAKE&BAKE]

YOU SHOULD HAVE A DIFFERENCE OF 15 TO 20 DEGREES FOR EXAMPLE IF THE INSIDE OF TRUCK IS 90 DEGREES YOU SHOULD BE GETTING AROUND 70 OUT OF VENTS IF YOU HAVE TOO MUCH FREON IN SYSTEM IT COULD BE KICKING OUT ON HIGH OVERLOAD MAKE SURE YOU KNOW FREON LEVELS ,IF YOU DONT KNOW HOW TO GET YOUR "SUPERHEAT"FIND SOMEONE WHO DOES